<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        a:hover{
            color: red;
        }
        .box:hover{
            color: green;
        }
    </style>
</head>
<body>
    <!-- 鼠标悬停状态 选择器：hover{css属性} -->
     <a href="#">a标签</a>
     <div class="box">div标签</div>
</body>
</html>